JP2011099379A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve ignitability while suppressing that temperature of an air-fuel mixture in a combustion chamber becomes excessively high. <P>SOLUTION: In an internal combustion engine of a spark ignition type in which the air-fuel mixture of air and fuel is ignited and burnt by spark discharge of an ignition plug, the ignition plug is arranged in a mounting hole of a cylinder head such that a discharge part is exposed inside the combustion chamber. A heat insulating material on the cylinder head side is arranged in an area on the surface of the cylinder head, which constitutes the combustion chamber, and between the mounting hole in which the ignition plug is arranged and an intake port or an exhaust port provided around the mounting hole. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine. More specifically, the present invention relates to a spark ignition type internal combustion engine that has an ignition plug and ignites and burns a mixture of air and fuel by discharge of the ignition plug.

  For example, Patent Document 1 discloses a self-ignition internal combustion engine having a glow plug in a combustion chamber. In the internal combustion engine of Patent Document 1, a heat insulating material is provided on the wall surface of the glow plug mounting hole of the cylinder head. According to Patent Document 1, this configuration maintains heat generation at the tip of the glow plug and suppresses heat loss of the glow plug.

Japanese Utility Model Publication No. 62-154235 Japanese Utility Model Publication No. 1-111423.

  Although Patent Document 1 is a technology related to a self-ignition internal combustion engine, a configuration capable of improving the ignitability is also desired for a spark ignition internal combustion engine. Here, it is also conceivable that the heat insulating material of Patent Document 1 is applied to a spark ignition internal combustion engine as it is, and for example, the heat insulating material is attached to the wall surface of the spark plug mounting hole. However, the heat insulating material provided on the wall surface of the glow plug mounting hole described above promotes self-ignition, while self-ignition that is not ignition by the spark plug in the spark ignition type internal combustion period, that is, pre-ignition etc. It can be an unfavorable situation. Therefore, the arrangement of the above-described heat insulating material cannot simply be applied to a spark ignition type internal combustion engine.

  Accordingly, an object of the present invention is to provide an internal combustion engine having a configuration capable of improving the ignitability of a spark plug in a spark ignition internal combustion engine.

In order to achieve the above object, a first invention includes a cylinder head, and a spark plug installed in a mounting hole of the cylinder head so that a discharge portion is exposed in a combustion chamber.
A spark ignition internal combustion engine that ignites and burns a mixture of air and fuel by spark discharge of the spark plug,
A cylinder head-side heat insulating material is provided in a region of the cylinder head on the surface constituting the combustion chamber and between the mounting hole and an intake port or an exhaust port provided around the mounting hole. Prepare.

  According to a second invention, in the internal combustion engine of the first invention, a piston-side heat insulating material is provided on a top surface of a piston disposed in a cylinder of the internal combustion engine and in a region facing the mounting hole. .

  According to a third aspect of the present invention, in the internal combustion engine of the second aspect, when projected in the stroke direction of the piston, the outer periphery of the region where the piston side heat insulating material is disposed and the cylinder head side heat insulating material are disposed. The outline of the region is the same.

  According to a fourth aspect of the present invention, in the internal combustion engine according to any one of the first to third aspects, the cylinder head-side heat insulating material has the intake port or the center around the mounting hole on the surface constituting the combustion chamber. Of the circle circumscribing the exhaust port, it is arranged inside the smallest circle.

According to a fifth aspect of the invention, in the internal combustion engine according to any one of the first to fourth aspects, the thermal resistance of the cylinder head side heat insulating material and / or the piston side heat insulating material is 0.001 [m ² K / W] or more. is there.

A sixth invention is the internal combustion engine of any one of the first to fifth inventions, wherein the internal combustion engine is a heat insulation engine,
The heat insulating property of the region where the cylinder head-side heat insulating material is disposed is higher than the heat insulating property of other regions constituting the combustion chamber.

  According to the first invention, the heat insulating material is arranged in the vicinity of the spark plug mounting hole on the surface constituting the combustion chamber of the cylinder head. The air-fuel mixture around the spark plug in the combustion chamber rises by receiving heat from this heat insulating material. Accordingly, at the time of ignition, only the air-fuel mixture around the spark plug that contributes to the generation of the initial flame of the air-fuel mixture can be effectively increased in temperature, and the ignitability can be improved. Further, the heat insulating material is attached only to the region between the spark plug and the intake / exhaust port. Therefore, the air-fuel mixture existing in the region outside the intake / exhaust port far from the spark plug has a low heat reception from the heat insulating material, and is kept at a low temperature as compared with the periphery of the spark plug. Therefore, the occurrence of pre-ignition due to excessive temperature rise can be prevented.

  According to the 2nd or 3rd invention, the heat insulating material is arrange | positioned at the piston top surface facing a spark plug attachment hole. Thereby, only the air-fuel mixture in the vicinity of the spark plug can be heated more effectively, and the ignitability can be improved.

  According to 4th invention, a heat insulating material is installed only in the area | region inside an intake / exhaust port. Therefore, the heat reception from the heat insulating material of the air-fuel mixture existing in the region outside the intake / exhaust port can be reliably suppressed to be small. As a result, it is possible to suppress an excessive temperature rise in the entire cylinder while raising the temperature of the air-fuel mixture around the spark plug.

  According to the fifth aspect of the invention, the air-fuel mixture around the plug can be effectively increased in temperature, and the ignitability can be improved.

  According to the sixth aspect of the invention, even in the heat insulation engine, the temperature of the air-fuel mixture around the spark plug can be effectively increased, and the ignitability can be improved.

It is a schematic diagram for demonstrating the ignition plug of the internal combustion engine of Embodiment 1 of this invention and the arrangement configuration of its periphery. It is a schematic diagram for demonstrating arrangement | positioning structure around the ignition plug of the cylinder head of the internal combustion engine of Embodiment 1 of this invention. It is a schematic diagram for demonstrating arrangement | positioning structure of the piston top surface of the internal combustion engine of Embodiment 1 of this invention. It is a schematic diagram for demonstrating the ignition plug of the internal combustion engine of Embodiment 2 of this invention, and the arrangement configuration of its periphery.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
FIG. 1 is a diagram for illustrating the configuration of a spark plug and its peripheral devices arranged in the internal combustion engine in the first embodiment of the present invention. The internal combustion engine of the first embodiment is a pent roof type internal combustion engine having two intake valves and an exhaust valve.

  As shown in FIG. 1, the internal combustion engine includes a cylinder block 10 and a cylinder head 12 disposed on the cylinder block 10. The cylinder block 10 has a cylindrical structure constituting a plurality of cylinders of the internal combustion engine, and a piston 14 is disposed in each cylinder.

  The cylinder head 12 has two intake ports 18 and 2 that pass through the cylinder head 12 and open to a surface (hereinafter referred to as “combustion chamber wall surface”) 16 a that constitutes the combustion chamber 16 of each cylinder. Two exhaust ports 20 are formed. The cylinder head 12 further has a mounting hole that opens near the center of the combustion chamber wall surface 16a, and a spark plug 22 is mounted in the mounting hole.

Heat insulating materials 24 and 26 are attached to the combustion chamber wall surface 16 a of the cylinder head 12 and the top surface 16 b of the piston 14 constituting the combustion chamber 16, respectively. The thermal resistance and thickness of the heat insulating materials 24 and 26 used here are adjusted so that the thermal resistance is 0.001 [m ² K / W] or more.

  FIG. 2 is a diagram illustrating a state in which combustion chamber wall surface 16a of the internal combustion engine according to Embodiment 1 of the present invention is viewed from the piston 14 side. As shown in FIG. 2, the combustion chamber wall surface 16a has two intake ports 18 that are opened and closed by an intake valve 18a and two exhaust ports 20 that are opened and closed by an exhaust valve 20a.

  The heat insulating material 24 is attached in a circle surrounding the spark plug 22 around the spark plug 22. The region where the heat insulating material 24 is installed is disposed in a region between the outer peripheral circle of the attachment hole of the spark plug 22 and the circle inside the intake valve 18a and the exhaust valve 20a with the spark plug 22 as the center.

  FIG. 3 is a diagram showing a top surface 16b of the piston 14 of the internal combustion engine according to the first embodiment of the present invention. FIG. 3 shows a state in which the surface of the piston head constituting the combustion chamber 16 is viewed from the cylinder head 12 side. As shown in FIG. 3, a heat insulating material 26 is attached near the center of the cylinder of the top surface 16 b of the piston 14. The region where the heat insulating material 26 is disposed is a region that is the same as the outer periphery of the heat insulating material 24 installation region of the cylinder head 12 when projected in the stroke direction.

  As described above, the heat insulating materials 24 and 26 are disposed around the spark plug 22. The air-fuel mixture receives heat from the heat insulating materials 24 and 26. Therefore, the temperature of the air-fuel mixture around the spark plug 22 can be increased effectively. On the other hand, in the region outside the intake / exhaust ports 18 and 20 and relatively far from the spark plug 22, the heat of the air-fuel mixture from the heat insulating materials 24 and 26 is extremely small. As described above, the configuration in which the heat insulating materials 24 and 26 are disposed only around the spark plug 22 can effectively raise the temperature of only the air-fuel mixture around the spark plug 22 that contributes to the generation of the initial flame. The thermal efficiency and ignitability can be improved. At the same time, since the air-fuel mixture can be kept at a relatively low temperature in a region away from the spark plug 22, excessive temperature rise in the entire cylinder can be suppressed.

  In this embodiment, the installation region of the heat insulating material 24 is a region between the outer peripheral circle of the attachment hole of the ignition plug 22 and the circle inside the intake port 18 and the exhaust port 20 of the combustion chamber wall surface 16a. Furthermore, the case where the installation area of the heat insulating material 26 on the piston 14 side is the same area as the installation area outline of the heat insulating material 24 on the cylinder head 12 side when projected in the piston stroke direction has been described. Thereby, only the air-fuel mixture around the spark plug 22 can be selectively heated.

  However, in this invention, if the installation area | region of the heat insulating materials 24 and 26 is an area | region around the spark plug 22, it will not restrict to this. However, the heat insulating material 24 on the cylinder head 12 side is attached to a region between the mounting hole of the spark plug 22 and the intake port 18 and the exhaust port 20, and the outline of the arrangement region of the heat insulating material 24 is as follows. A circle smaller than the smallest circle among the circles circumscribing the intake port 18 or the exhaust port 20 is preferable.

  Moreover, the shape at the time of projecting the arrangement position of the heat insulating material 24 on the combustion chamber wall surface 16a side and the heat insulating material 26 on the piston top surface 16b side in the stroke direction may not be the same. As long as the heat insulating material 26 on the top surface 16b of the piston 14 is in the vicinity of the spark plug 22, the heat insulating material 26 can be arranged in another region or in another arrangement shape. Furthermore, the heat insulating material is not limited to those having the heat insulating materials 24 and 26 on the combustion chamber wall surface 16a and the piston top surface 16b, respectively. For example, the heat insulating material is installed only around the ignition plug 22 on the combustion chamber wall surface 16a side. Also good. The arrangement region of the heat insulating material 24 or the heat insulating material 26 is the same in the following embodiments.

  In the first embodiment, the case where the present invention is applied to a pent roof type internal combustion engine has been described. However, the present invention is not limited to this, for example, an internal combustion engine having only one intake valve and one exhaust valve. The present invention can also be applied to other internal combustion engines. Also in this case, the air-fuel mixture can be effectively heated to a high temperature by installing a heat insulating material in a region between the outer periphery of the spark plug and the intake port or the exhaust port. Thereby, the ignitability of the internal combustion engine can be improved while suppressing an excessive temperature rise. The same applies to the following embodiments.

  Further, when the internal combustion engine is a heat insulating engine, the heat insulating material is similarly installed so that the heat insulating property in the area around the spark plug 22 is higher than in other areas. Thereby, the temperature of the air-fuel mixture around the spark plug 22 can be effectively increased, and the ignitability of the internal combustion engine can be improved. The same applies to the following embodiments.

  In addition, the thermal resistance of the heat insulating material in the present invention is not limited to that described in this embodiment. The same applies to the following embodiments.

Embodiment 2. FIG.
FIG. 4 is a schematic diagram for explaining the configuration of an ignition plug of an internal combustion engine and its peripheral devices in Embodiment 2 of the present invention. The example shown in FIG. 4 is the same as the configuration of FIG. 1 except for the shape of the arrangement of the protruding portion of the spark plug into the combustion chamber 16 and the surrounding heat insulating material. Specifically, the spark plug 30 of FIG. 4 is installed in the combustion chamber 16 so that not only the electrode for discharge but also a part of the tip protrudes.

  The heat insulating material 32 on the cylinder head 12 side is attached to the wall surface of the combustion chamber 16 so as to fill the protruding portion of the spark plug 30. The state in which the combustion chamber wall surface 16a is projected in the stroke direction is the same as in FIG. That is, it is installed in a region between the outer periphery of the mounting hole of the spark plug 30 and the circle inside the intake port 18 and the exhaust port. Further, the heat insulating material 26 on the piston 14 side is also arranged in the same region as the region where the arrangement region of the heat insulating material 32 is projected in the stroke direction, as in FIG.

  As described above, by disposing the heat insulating material 32 so as to cover the protruding portion of the spark plug 30 into the combustion chamber 16, the temperature of the air-fuel mixture around the spark plug 30 can be more reliably increased, and ignition is performed. Can be improved.

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., the reference is made unless otherwise specified or the number is clearly specified in principle. The invention is not limited to the numbers. Further, the structure and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

DESCRIPTION OF SYMBOLS 10 Cylinder block 12 Cylinder head 14 Piston 16 Combustion chamber 18 Intake port 18a Intake valve 20 Exhaust port 20a Exhaust valve 22, 30 Spark plug 24, 26, 32 Thermal insulation

Claims (6)

A cylinder head, and a spark plug installed in the mounting hole of the cylinder head so that the discharge part is exposed in the combustion chamber,
In a spark ignition internal combustion engine that ignites and burns a mixture of air and fuel by spark discharge of the spark plug,
A cylinder head-side heat insulating material is provided in a region of the cylinder head on the surface constituting the combustion chamber and between the mounting hole and an intake port or an exhaust port provided around the mounting hole. An internal combustion engine comprising:   2. The internal combustion engine according to claim 1, further comprising a piston-side heat insulating material on a top surface of a piston disposed in a cylinder of the internal combustion engine and in a region facing the mounting hole.   The outer contour of the region where the piston-side heat insulating material is disposed and the outer contour of the region where the cylinder head-side heat insulating material is disposed are the same when projected in the stroke direction of the piston. 2. The internal combustion engine according to 2.   The cylinder head side heat insulating material is disposed on the inner surface of the smallest circle among the circles circumscribing the intake port or the exhaust port, with the mounting hole as a center, on the surface constituting the combustion chamber. The internal combustion engine according to any one of claims 1 to 3, wherein: 5. The internal combustion engine according to claim 1, wherein a thermal resistance of the cylinder head side heat insulating material and / or the piston side heat insulating material is 0.001 [m ² K / W] or more. . The internal combustion engine is an adiabatic engine,
6. The internal combustion engine according to claim 1, wherein a heat insulating property of a region where the cylinder head-side heat insulating material is disposed is higher than a heat insulating property of another region constituting the combustion chamber. organ.

Images